There was at least one large blast followed by a series of smaller ones. Police set up a security perimeter and cleared the area around the industrial park.

One man who lives nearby said: "I was working in the garage and I heard a loud, 'Boom.' Then we were evacuated.'' Another neighbour said the flames were visible from blocks away. Both declined to give their names.

Within minutes of the blast, police said, employees had been evacuated from the facility and supervisors were performing a head count outdoors.